The Query Builder enables you to add a column to your query that is calculated from other columns or values.
In your query you want to create a calculated column that contains the profit that is earned from each order. The Products data set contains the variable UnitPrice, which is the retail price of the product. The Orders data set contains the variables UPRICE, which is the cost, and QUANTITY, which is the number sold. From these three variables, you can calculate the profit that is earned from each order.